Ruthenium (II) Complexes and Their Use as AntiCancer Agents

§103 §112

DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Election/Restrictions Applicant’s election with traverse of Group I (drawn to a compound/pharmaceutical composition), and the species recited in claim 7, in the reply filed on 05/23/2024 is acknowledged. Claims 1, 3-7, 11, 14-23 are pending of which (claims 14-17, 20-23) are withdrawn from further consideration pursuant to 37 CFR 1.142(b) as being drawn to a nonelected INVENTION, there being no allowable generic or linking claim. The restriction requirement is still deemed proper and is made Final. Pending claims 1, 3-7, 11, 18-19 have been examined on the merits. Please note, for clarity of the record, Applicant’s election of the species of compound recited in claim 7, having the following structure: PNG media_image1.png 367 499 media_image1.png Greyscale corresponding claim 1’s genus when R5, R6, R8, R9 are hydrogen; R1, R2, R3, R4 are aryl; O=Y=O is a dioxolane ligand in the form of semiquinone, PNG media_image2.png 144 130 media_image2.png Greyscale , wherein R31 is OR34 where R34 is an alkyl; m is +1; X- is PF6-, reading on claims 1, 3-7, 11 and 18-19. Withdrawn Rejections The rejection of claims 1, 3-7, 11, 18-19 under 35 U.S.C. 103 as being unpatentable over CN107417736B in view of Ghosh et al. (J Biol. Inorg. Chem. 2005 Aug; 10(5):496-508), Wada et al. (Inorg. Chem. 2006 Oct 30; 45(22):8887-94) and Pyle et al. (J. of the Amer Chem Soc, 111(8), 3051–3058). As evidence by Notaro A. et al. (J Med. Chem. 2020 May 28; 63(10):5568-5584. All references are being made to the English translation (machine generated). The Chinese version can be found at the end of the English translated version is withdrawn in view of the claim amendment. Claim interpretation Claim 1 is interpreted to recite two alternatives: 1). A genus of compounds defined by formula (I-A), including various substituents and a ligand option; or 2). The specifically listed compounds following the phrase “or.” New Grounds of Rejection due to the Applicant’s Claim Amendments Claim Rejections - 35 USC § 112 The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claim 6 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Claim 1 recites the following: PNG media_image3.png 408 720 media_image3.png Greyscale However, superscript “m+ and m” are not defined, nor have a clear meaning for the term have been provided. This creates ambiguity as to how “m+ and m” are intended to limit the claimed subject matter. Appropriate correction is required New Grounds of Rejection due to the Applicant’s Claim Amendments In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action. The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows: 1. Determining the scope and contents of the prior art. 2. Ascertaining the differences between the prior art and the claims at issue. 3. Resolving the level of ordinary skill in the pertinent art. 4. Considering objective evidence present in the application indicating obviousness or Non-obviousness. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention. Claims 1, 3-7, 11, 18-19 are rejected under 35 U.S.C. 103 as being unpatentable over CN107417736B “CN ‘736” in view of Ghosh et al. (J Biol. Inorg. Chem. 2005 Aug; 10(5):496-508), Wada et al. (Inorg. Chem. 2006 Oct 30; 45(22):8887-94), Pyle et al. (J. of the Amer Chem Soc, 111(8), 3051–3058), García-Cañadas at. al., Angew Chem Int Ed Engl. 2003 Jul 7;42(26):3011-4, Gransbury et al., Inorg Chem, vol. 58, no. 7, Apr. 2019, pp. 4230–43. All references are being made to the English translation (machine generated). The Chinese version can be found at the end of the English translated version. Regarding claims 1, 3-7, 11, and 18-19, CN ‘736 in ([0018], emphasis added) teaches a compound Ru(DIP)2(SA) wherein R1 to R4 are phenyl; R5, R6, R8 and R9 are each hydrogen, with salicylic acid ligand occupies the remaining ligand coordination site of the Ru(DIP)2 core. PNG media_image4.png 253 264 media_image4.png Greyscale CN ‘736 (abstract) teaches that ruthenium complex exhibits anticancer or antitumor activity in vitro. CN ‘736 ([0007]) also discloses that one of the major mechanisms of ruthenium complex is targeting DNA, comparable to instant claim (specification page 37). Although CN ‘736 does not explicitly identify any particular pharmaceutically acceptable excipient, however, CN ‘736 ([0112]-[0124]) discloses the compounds were used as anticancer cancer drugs and were used in cell-culture. Thus, a POSITA would infer that the compounds were intended for pharmaceutical/therapeutic use. Therefore, a POSITA would mix the compounds in an appropriate pharmaceutical excipient before administration. However, CN ‘736 does not explicitly teach presence of dioxolene or semiquinone ligand interact with Ru(DIP)2. However, Wada (page 8887, scheme 1) teaches redox series of RuII/III-dioxolene complexes once incorporating as an O, O chelating ligand in a ruthenium polypyridyl complex, in particularly to form RuIII-semiquinine. Wada (page 8887, scheme 2) teaches that varying the substituents on the dioxolane ligand predictably shifts the electronic structure between these forms which may be critical for the compound properties. PNG media_image5.png 406 804 media_image5.png Greyscale This is supported by Ghosh (496-497, Figure 1; page 500-501, emphasis added) disclosing that PNG media_image6.png 215 246 media_image6.png Greyscale the salt form analogs of ruthenium (II) complexes can bear PF6- counterion, wherein m+ is +, (X-)m is PF6- ; for example Ru(phen)2(bsq)](PF6). Ghosh (page 500, 502) also discloses PF6- counterion is used to stabilize cationic ruthenium complexes and confirms the presence of semiquinone species via electron paramagnetic resonance (EPR) activity. Moreover, Gosh (page 505 and 507) discloses exposure of [Ru(bpy)2(sq), as an example, to complex to DNA, resulting in changes in the ligand as well as DNA binding, causing reduction of the ligand to the corresponding catechol, thus, allowing the complex to function as a mild redox agent for selective DNA modification. Therefore, a POSITA would have been motivated to optimize the anticancer cancer property of Ru(DIP)2(SA), by modifying the teachings of CN ‘736 and replace the salicylic acid with a dioxolene O,O-ligand and incorporating PF6- counterion to improve the stability, solubility and characterization of ruthenium (II) complexes. This modification would ensure stronger binding of Ru(DIP)2 framework with DNA, coordinated by the semiquinone ligand. This is also supported by this redox flexibility, allowing the ruthenium complex not only to bind to DNA but also to participate in chemical electron transfer through their unique electron delocalization which enables reversible redox activity. This is supported by the specification (page 37, line 29-32) PNG media_image7.png 114 738 media_image7.png Greyscale Therefore, incorporating a dioxolane ligand into the complex can further enhance this interaction, as the redox versatility of dioxolane enable not only binding but also dynamic electron transfer processes, potentially enhancing their impact on DNA interaction. Therefore, it would have been obvious to a POSITA to modify the CN ’736’ teachings in view of Gosh and Wade by replacing salicylic acid ligand with dioxolane to arrive at the claimed invention, because of the unique electrochemical properties and dynamic DNA interactions, enhancing the complex activity such as catalysis or targeted biological intervention. PNG media_image8.png 220 598 media_image8.png Greyscale The other possibility is modifying Gosh’s teaching in view of CN’ 736, this is because Pyle (page 3057, right col.; page 3052, Figure 3) teaches ruthenium complex containing DIP core structure which has a higher binding affinity to DNA because of larger surface area and non-planarity compared to phen core structure. In fact, Pyle (page 3057, right col.; page 3052, Figure 3) teaches ruthenium complex containing DIP core structure PNG media_image9.png 108 182 media_image9.png Greyscale is better than phen PNG media_image10.png 92 122 media_image10.png Greyscale , thus it would have been reasonable to a POSITA to consider modifying Gosh’s teachings in view of Pyle and CN ‘736 by considering to replace phen core structure with DIP to come to [Ru(DIP)2(bsq)] (PF6) and arrive at the claimed invention. Therefore, it would have been prima facie obvious to a POSITA to combine the teachings of Gosh and CN in view of Pyle and Wade, on the use of ruthenium complex compound as anticancer drugs, to arrive at the claimed invention. A POSITA would have been motivated to do so because CN ‘763 teaches Ru (DIP)2 with a more favorable IC50 against certain cancer cell lines in vitro, Pyle teaches a ruthenium complex with DIP core structure exhibits a stronger binding affinity to DNA compared to phen core structure, and Wade discloses a wide range capability of dioxolane ligand binding to ruthenium (II). Regarding dioxolane substituents, Wada (page 8887-8888, Scheme 2) teaches dioxolane may be systematically substituted with alkyl and chloro groups. This furthermore supported by García-Cañadas (page 3012) disclosing a derivative of [Ru(bpy)2(Cl4cat)] having the following structure, which concept is comparable to Wada’s disclosure (page 8888, Scheme): PNG media_image11.png 412 358 media_image11.png Greyscale PNG media_image12.png 454 470 media_image12.png Greyscale Gransbury also demonstrates that variation of ring substituents between halogen and alkyl group, is a routine and predictable substituent for controlling redox and electronic properties of the metal complex. Therefore, it would have been obvious for a person of ordinary skill in the art (POSITA) to modify CN ‘736’s teachings in view of García-Cañadas, Ghosh and Gransbury to arrive at the claim invention, due to relative improvement in stability and valence tautomerism. PNG media_image13.png 479 545 media_image13.png Greyscale As evidence by Heike’s disclosure (page 29888-29892) of halogens substituents withdraw electron density from the catecholate ligand, make it more electron-poor and harder to oxidize. Thus, this electronic effect stabilizes lower-energy ligand states and shifts redox processes to more positive potential, strongly influencing valence and thus stabilizing the metal complex. (Hieke et al., ACS Omega, vol. 10, no. 27, July 2025, pp. 29888–98.) PNG media_image14.png 328 370 media_image14.png Greyscale Therefore, such disclosure would have suggested to a POSITA that electronic and redox properties of Ru-dioxolene complex would further varied by modifying substituents on the dioxolane ligand. Therefore, it would have been prima facie obvious to a POSITA to modify the teachings of CN ‘736 in view of Gosh, Wada’s, and Wada by replacing salicylic acid of Ru(DIP)2(SA) with dioxolane and/or dioxolene substituents, including chloro and tert-butyl substituent to optimize the compound efficacy, and to arrive at the claimed invenetion. PNG media_image15.png 200 400 media_image15.png Greyscale Response To Argument Applicant argues that the Examiner’s comparison of the compounds inhibition activity was inaccurate, because the comparison was mainly between Ru(DIP)2Cl2 and Ru(DIP)2(SA), prior art. Applicant also points to compounds 1, 2, 3, and 6 as exhibiting strong cytotoxicity to indicate unexpected results. The Examiner acknowledged Applicant’s augment, however, the data, when considered as a whole do not establish an unexpected result as claimed. Applicant has not established what structural feature is responsible for the unexpected results, for instance, whether it is attributed to the dioxolane/semiquinone ligand itself or to the substituents. The specification (page 35, line 5-9) attributes the differences in cytotoxicity to the electron density of the organic moiety, which indicates that the observed activity may depend upon the substituent and its electronic effect rather being inherent property of the dioxolene/semiquinone core. Furthermore, in HeLA, compound 5 and 8 have IC50(µM) and 10.46, respectively; whereas compound 4 has an IC50(µM) of 0.124. Thus, the data demonstrates substantial substituent dependent variation in cytotoxicity rather than a uniform property attributed to the dioxolene/semiquinone ligand framework. Even if the activity of a particular compound, such as compound 4, is unexpected; Applicant has not demonstrated that the claimed unexpected cytotoxicity is attributed to the claimed dioxolene/semiquinone structure, nor do that property is commensurate with full scope of the claims. Applicant argues that Examiner improperly concluded that eh salicylate ligand does not involve or participate in DNA binding, because the DNA interaction is mainly driven by of Ru(phen)2 or Ru(DIP)2 CORE. Applicant cites “Both ancillary and intercalative ligands play a crucial role in interaction with DNA” and argues that such teaching establishes that the ligand coordinated to the ruthenium center contribute to DNA binding. Applicant’s argument is not persuasive because cited text does not establish that all ligands coordinated to a ruthenium polypyridyl complex necessarily participate in DNA binding. It is important to keep in mind, the reference discusses intercalative ligands with distinct ligands, and Dive (page 2, emphasis added) discloses “The ligands PyIP, FyIP and IIP were prepared by the condensation of 1,10-phenanthroline-5,6-dione with respective aldehydes according to the literature methods.” Thus, PNG media_image16.png 222 770 media_image16.png Greyscale the prior art discloses a different type of ruthenium polypyridyl complex and does not establish that a O, O-chelating salicylate ligand would likewise participate in DNA binding. Applicant argues that Gosh does not teach that the compounds possess anticancer property. Applicant’s argument is not persuasive. In response to Applicant’s arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). Therefore, Applicant should consider the combined teachings of the prior art as a collective disclosure for the obviousness rejection, rather on differences found in any single prior art. Applicant argues that, although the prior art discloses halogen and alkyl substituents on bidentate dioxolane ligands, however, the prior art uses cobalt instead of ruthenium. The prior art also does not provide motivation to use those substituted dioxolane ligands with ruthenium. Applicant’s argument is not persuasive because cobalt and ruthenium are both d-block transition metals capable of coordinating O,O-chelating ligands. It is important to note that both the halogens and alkyl substitutions are modifications to the dioxolane ligand itself, rather than to the metal, thus, the cobalt disclosure provides a reason for a POSITA to consider such ligand modifications in the related ruthenium complex. Conclusion Therefore, claims 1,3-7, 11, and 18-19 are rejected. Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action. 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To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /P.P.E./Examiner, Art Unit 1622 /JAMES H ALSTRUM-ACEVEDO/Supervisory Patent Examiner, Art Unit 1622